1. Technical Field
The present invention relates to a contactor failure determining method and a contactor failure determining device for determining failures in a contactor in a battery pack.
2. Related Art
In the related art, in a battery pack mounted on an electric vehicle such as an electric car or a hybrid car, contactors (a positive-side contactor and a negative-side contactor) are provided between a multi-cell battery and terminals of the battery pack in order to isolate the multi-cell battery which is a high-voltage power supply from the outside when an unexpected event such as an accident occurs.
Moreover, a precharge contactor is provided in the battery pack in parallel to the positive-side contactor so as to suppress an inrush current at the activation of a high-voltage power supply.
The contactors are safety mechanisms of a battery pack and it is necessary to periodically check whether these contactors operate properly. Thus, the contactor is opened and closed at the activation (the start of supply of high-voltage power) and the deactivation (the end of supply of high-voltage power) of an electric vehicle to determine whether a failure has occurred in the contactor. The reason why contactor failures are determined at the activation and the deactivation of the electric vehicle is that since it is not possible to open and close the contactor during traveling of the electric vehicle, it is necessary to stably input and output power to a load during traveling (during the use of high-voltage power) of the electric vehicle.
For example, JP-A-2013-169087 below discloses a technique of diagnosing abnormalities by melting and fixing in a negative-side contactor and a precharge contactor at the timing of outputting an activation command for activating a vehicle to a positive-side contactor, the negative-side contactor, and the precharge contactor and diagnosing abnormalities by melting and fixing in the positive-side contactor at the timing of outputting a deactivation command for stopping the vehicle.
When contactor failure determination is performed at the activation and deactivation of an electric vehicle as in the conventional technique, a driver may experience inconvenience because activation and deactivation of the electric vehicle takes a longer period than gasoline vehicles.
Thus, failures in the contactors are preferably determined as quickly as possible.
The present invention has been made in view of such a problem and an object thereof is to provide a contactor failure determining method and a contactor failure determining device capable of determining failures in contactors quickly.